Method and apparatus for applying assistance information for traffic steering in wireless communication system

ABSTRACT

A method and apparatus for applying assistance information for traffic steering between a 3rd generation partnership project (3GPP) access network and a non-3GPP access network in a wireless communication system is provided. A user equipment (UE) receives assistance information for traffic steering through a dedicated signaling from an eNodeB (eNB), and starts a timer upon entering an idle mode. The UE applies the assistance information received through the dedicated signaling until the timer expires. After the timer expires, the UE applies assistance information received through a broadcast signaling.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to wireless communications, and moreparticularly, to a method and apparatus for applying assistanceinformation for traffic in a wireless communication system.

2. Related Art

Universal mobile telecommunications system (UMTS) is a 3rd generation(3G) asynchronous mobile communication system operating in wideband codedivision multiple access (WCDMA) based on European systems, globalsystem for mobile communications (GSM) and general packet radio services(GPRS). A long-term evolution (LTE) of UMTS is under discussion by the3rd generation partnership project (3GPP) that standardized UMTS.

3GPP/wireless local area network (WLAN) interworking has been discussed.3GPP/WLAN interworking may be called traffic steering. From rel-8 of3GPP LTE, access network discovery and selection functions (ANDSF) fordetecting and selecting accessible access networks have beenstandardized while interworking with non-3GPP access (e.g., WLAN) isintroduced. The ANDSF may carry detection information of access networksaccessible in location of a user equipment (UE) (e.g., WLAN, WiMAXlocation information, etc), inter-system mobility policies (ISMP) whichis able to reflect operator's policies, and inter-system routing policy(ISRP). Based on the information described above, the UE may determinewhich IP traffic is transmitted through which access network. The ISMPmay include network selection rules for the UE to select one activeaccess network connection (e.g., WLAN or 3GPP). The ISRP may includenetwork selection rules for the UE to select one or more potentialactive access network connection (e.g., both WLAN and 3GPP). The ISRPmay include multiple access connectivity (MAPCON), IP flow mobility(IFOM) and non-seamless WLAN offloading. Open mobile alliance (OMA)device management (DM) may be used for dynamic provision between theANDSF and the UE.

The MAPCON is a standardization of a technology which enablesconfiguring and maintaining multiple packet data network (PDN)connectivity simultaneously through 3GPP access and non-3GPP access, andenables a seamless traffic offloading in units of all active PDNconnections. For this, an ANDSF server provides access point name (APN)information for performing offloading, routing rule, time of dayinformation, and validity area information, etc.

The IFOM supports mobility in a unit of IP flow, which is more flexibleand more segmented than the MAPCON, and seamless offloading. The IFOMenables access to different access networks even when the UE isconnected to a PDN using the same APN, which is different from theMAPCON. The IFOM also enables mobility in a unit of specific IP trafficflow, not a unit of PDN, for a unit of mobility or offloading, andaccordingly, services may be provided flexibly. For this, an ANDSFserver provides IP flow information for performing offloading, routingrule, time of day information, and validity area information, etc.

The non-seamless WLAN offloading is a technology that offloads trafficscompletely so as not to go through the EPC as well as that changes apath of a specific IP traffic to WLAN. The offloaded IP traffic cannotbe moved to 3GPP access seamlessly again since anchoring is notperformed to the P-GW for mobility support. For this, an ANDSF serverprovides information as similar as the information provided for theIFOM.

Besides the ANDSF described above, in 3GPP, a method in which a radioaccess network (RAN) (i.e., base station (BS), radio network controller(RNC)) provides assistance information for traffic steering between3GPP/WLAN to a UE and the UE performs traffic steering using thereceived assistance information according to a rule defined by an accessstratum standard, for a case that an ANDSF policy is not provided to theUE, has been discussed currently.

The assistance information for traffic steering may be updated dependingon overall network situation. However, it is not clear when and how theUE acquires the updated assistance information. Accordingly, a methodfor handling assistance information effectively is required.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for applyingassistance information in a wireless communication system. The presentinvention provides a method for handling assistance information fortraffic steering between a 3rd generation partnership project (3GPP)access network and a non-3GPP access network. The present inventionprovides a method for applying, by a user equipment (UE), assistanceinformation for traffic steering between the 3GPP access network and thenon-3GPP access network, which is received by a dedicated signaling, fora specific period of time even after the UE enters an idle mode.

In an aspect, a method for applying, by a user equipment (UE),assistance information for traffic steering between a 3rd generationpartnership project (3GPP) access network and a non-3GPP access networkin a wireless communication system is provided. The method includesreceiving first assistance information for traffic steering through adedicated signaling from an eNodeB (eNB), receiving second assistanceinformation for traffic steering through a broadcast signaling from theeNB, starting a timer upon entering an idle mode, applying the firstassistance information received through the dedicated signaling untilthe timer expires, and applying the second assistance informationreceived through the broadcast signaling after the timer expires.

The first assistance information may include a time value for the timerwhich indicates a period of time during which the first assistanceinformation is valid.

The first assistance information may be valid in a cell from which thefirst assistance information is received.

The method may further include releasing the first assistanceinformation upon determining that the first assistance information isinvalid.

It may be determined that first assistance information is invalid when aserving cell is changed.

The serving cell may be changed when handover, cell selection or cellreselection is performed.

The first assistance information may include area information indicatingan area in which the first assistance information is valid.

The first assistance information or the second assistance informationmay include at least one of thresholds regarding the 3GPP accessnetwork, thresholds regarding the non-3GPP access network, identifiersof the non-3GPP access network, or traffic routing information.

The first assistance information may be received via a radio resourcecontrol (RRC) connection reconfiguration message.

The second assistance information may be received via systeminformation.

The applying the first assistance information may include performingtraffic steering from the 3GPP access network to the non-3GPP accessnetwork or from the non-3GPP access network to the 3GPP access networkbased on the first assistance information.

The applying the second assistance information may include performingtraffic steering from the 3GPP access network to the non-3GPP accessnetwork or from the non-3GPP access network to the 3GPP access networkbased on the second assistance information.

The method may further include establishing an RRC connection with theeNB after the timer expires, and transmitting the first assistanceinformation and the expiry of the first assistance information uponestablishing the RRC connection with the eNB.

In another aspect, a user equipment (UE) in a wireless communicationsystem is provided. The UE includes a radio frequency (RF) unit fortransmitting or receiving a radio signal, and a processor coupled to theRF unit, and configured to receive first assistance information fortraffic steering between a 3rd generation partnership project (3GPP)access network and a non-3GPP access network through a dedicatedsignaling from an eNodeB (eNB), receive second assistance informationfor traffic steering through a broadcast signaling from the eNB, start atimer upon entering an idle mode, apply the first assistance informationreceived through the dedicated signaling until the timer expires, andapply the second assistance information received through the broadcastsignaling after the timer expires.

Traffic of UEs in an idle mode as well as traffic of UEs in a connectedmode can be steered effectively between a 3GPP access network and anon-3GPP access network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows LTE system architecture.

FIG. 2 shows a control plane of a radio interface protocol of an LTEsystem.

FIG. 3 shows a user plane of a radio interface protocol of an LTEsystem.

FIG. 4 shows an example of a physical channel structure.

FIG. 5 shows a graphical representation of Wi-Fi channels in 2.4 GHzband.

FIG. 6 shows an example of a method for applying assistance informationfor traffic steering according to an embodiment of the presentinvention.

FIG. 7 shows an example of a method for applying assistance informationfor traffic steering according to another embodiment of the presentinvention.

FIG. 8 shows an example of a method for applying assistance informationfor traffic steering according to another embodiment of the presentinvention.

FIG. 9 shows a wireless communication system to implement an embodimentof the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The technology described below can be used in various wirelesscommunication systems such as code division multiple access (CDMA),frequency division multiple access (FDMA), time division multiple access(TDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), etc. The CDMA canbe implemented with a radio technology such as universal terrestrialradio access (UTRA) or CDMA-2000. The TDMA can be implemented with aradio technology such as global system for mobile communications(GSM)/general packet ratio service (GPRS)/enhanced data rate for GSMevolution (EDGE). The OFDMA can be implemented with a radio technologysuch as institute of electrical and electronics engineers (IEEE) 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, evolved UTRA (E-UTRA), etc.IEEE 802.16m is evolved from IEEE 802.16e, and provides backwardcompatibility with a system based on the IEEE 802.16e. The UTRA is apart of a universal mobile telecommunication system (UMTS). 3rdgeneration partnership project (3GPP) long term evolution (LTE) is apart of an evolved UMTS (E-UMTS) using the E-UTRA. The 3GPP LTE uses theOFDMA in a downlink and uses the SC-FDMA in an uplink. LTE-advanced(LTE-A) is an evolution of the LTE.

For clarity, the following description will focus on LTE-A. However,technical features of the present invention are not limited thereto.

FIG. 1 shows LTE system architecture. The communication network iswidely deployed to provide a variety of communication services such asvoice over internet protocol (VoIP) through IMS and packet data.

Referring to FIG. 1, the LTE system architecture includes one or moreuser equipment (UE; 10), an evolved-UMTS terrestrial radio accessnetwork (E-UTRAN) and an evolved packet core (EPC). The UE 10 refers toa communication equipment carried by a user. The UE 10 may be fixed ormobile, and may be referred to as another terminology, such as a mobilestation (MS), a user terminal (UT), a subscriber station (SS), awireless device, etc.

The E-UTRAN includes one or more evolved node-B (eNB) 20, and aplurality of UEs may be located in one cell. The eNB 20 provides an endpoint of a control plane and a user plane to the UE 10. The eNB 20 isgenerally a fixed station that communicates with the UE 10 and may bereferred to as another terminology, such as a base station (BS), a basetransceiver system (BTS), an access point, etc. One eNB 20 may bedeployed per cell. There are one or more cells within the coverage ofthe eNB 20. A single cell is configured to have one of bandwidthsselected from 1.25, 2.5, 5, 10, and 20 MHz, etc., and provides downlinkor uplink transmission services to several UEs. In this case, differentcells can be configured to provide different bandwidths.

Hereinafter, a downlink (DL) denotes communication from the eNB 20 tothe UE 10, and an uplink (UL) denotes communication from the UE 10 tothe eNB 20. In the DL, a transmitter may be a part of the eNB 20, and areceiver may be a part of the UE 10. In the UL, the transmitter may be apart of the UE 10, and the receiver may be a part of the eNB 20.

The EPC includes a mobility management entity (MME) which is in chargeof control plane functions, and a system architecture evolution (SAE)gateway (S-GW) which is in charge of user plane functions. The MME/S-GW30 may be positioned at the end of the network and connected to anexternal network. The MME has UE access information or UE capabilityinformation, and such information may be primarily used in UE mobilitymanagement. The S-GW is a gateway of which an endpoint is an E-UTRAN.The MME/S-GW 30 provides an end point of a session and mobilitymanagement function for the UE 10. The EPC may further include a packetdata network (PDN) gateway (PDN-GW). The PDN-GW is a gateway of which anendpoint is a PDN.

The MME provides various functions including non-access stratum (NAS)signaling to eNBs 20, NAS signaling security, access stratum (AS)security control, Inter core network (CN) node signaling for mobilitybetween 3GPP access networks, idle mode UE reachability (includingcontrol and execution of paging retransmission), tracking area listmanagement (for UE in idle and active mode), P-GW and S-GW selection,MME selection for handovers with MME change, serving GPRS support node(SGSN) selection for handovers to 2G or 3G 3GPP access networks,roaming, authentication, bearer management functions including dedicatedbearer establishment, support for public warning system (PWS) (whichincludes earthquake and tsunami warning system (ETWS) and commercialmobile alert system (CMAS)) message transmission. The S-GW host providesassorted functions including per-user based packet filtering (by e.g.,deep packet inspection), lawful interception, UE Internet protocol (IP)address allocation, transport level packet marking in the DL, UL and DLservice level charging, gating and rate enforcement, DL rate enforcementbased on APN-AMBR. For clarity MME/S-GW 30 will be referred to hereinsimply as a “gateway,” but it is understood that this entity includesboth the MME and S-GW.

Interfaces for transmitting user traffic or control traffic may be used.The UE 10 and the eNB 20 are connected by means of a Uu interface. TheeNBs 20 are interconnected by means of an X2 interface. Neighboring eNBsmay have a meshed network structure that has the X2 interface. The eNBs20 are connected to the EPC by means of an S1 interface. The eNBs 20 areconnected to the MME by means of an S1-MME interface, and are connectedto the S-GW by means of S1-U interface. The S1 interface supports amany-to-many relation between the eNB 20 and the MME/S-GW.

The eNB 20 may perform functions of selection for gateway 30, routingtoward the gateway 30 during a radio resource control (RRC) activation,scheduling and transmitting of paging messages, scheduling andtransmitting of broadcast channel (BCH) information, dynamic allocationof resources to the UEs 10 in both UL and DL, configuration andprovisioning of eNB measurements, radio bearer control, radio admissioncontrol (RAC), and connection mobility control in LTE ACTIVE state. Inthe EPC, and as noted above, gateway 30 may perform functions of pagingorigination, LTE_IDLE state management, ciphering of the user plane, SAEbearer control, and ciphering and integrity protection of NAS signaling.

FIG. 2 shows a control plane of a radio interface protocol of an LTEsystem. FIG. 3 shows a user plane of a radio interface protocol of anLTE system.

Layers of a radio interface protocol between the UE and the E-UTRAN maybe classified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of the open systeminterconnection (OSI) model that is well-known in the communicationsystem. The radio interface protocol between the UE and the E-UTRAN maybe horizontally divided into a physical layer, a data link layer, and anetwork layer, and may be vertically divided into a control plane(C-plane) which is a protocol stack for control signal transmission anda user plane (U-plane) which is a protocol stack for data informationtransmission. The layers of the radio interface protocol exist in pairsat the UE and the E-UTRAN, and are in charge of data transmission of theUu interface.

A physical (PHY) layer belongs to the L1. The PHY layer provides ahigher layer with an information transfer service through a physicalchannel. The PHY layer is connected to a medium access control (MAC)layer, which is a higher layer of the PHY layer, through a transportchannel. A physical channel is mapped to the transport channel. Data istransferred between the MAC layer and the PHY layer through thetransport channel. Between different PHY layers, i.e., a PHY layer of atransmitter and a PHY layer of a receiver, data is transferred throughthe physical channel using radio resources. The physical channel ismodulated using an orthogonal frequency division multiplexing (OFDM)scheme, and utilizes time and frequency as a radio resource.

The PHY layer uses several physical control channels. A physicaldownlink control channel (PDCCH) reports to a UE about resourceallocation of a paging channel (PCH) and a downlink shared channel(DL-SCH), and hybrid automatic repeat request (HARQ) information relatedto the DL-SCH. The PDCCH may carry a UL grant for reporting to the UEabout resource allocation of UL transmission. A physical control formatindicator channel (PCFICH) reports the number of OFDM symbols used forPDCCHs to the UE, and is transmitted in every subframe. A physicalhybrid ARQ indicator channel (PHICH) carries an HARQ acknowledgement(ACK)/non-acknowledgement (NACK) signal in response to UL transmission.A physical uplink control channel (PUCCH) carries UL control informationsuch as HARQ ACK/NACK for DL transmission, scheduling request, and CQI.A physical uplink shared channel (PUSCH) carries a UL-uplink sharedchannel (SCH).

FIG. 4 shows an example of a physical channel structure.

A physical channel consists of a plurality of subframes in time domainand a plurality of subcarriers in frequency domain. One subframeconsists of a plurality of symbols in the time domain. One subframeconsists of a plurality of resource blocks (RBs). One RB consists of aplurality of symbols and a plurality of subcarriers. In addition, eachsubframe may use specific subcarriers of specific symbols of acorresponding subframe for a PDCCH. For example, a first symbol of thesubframe may be used for the PDCCH. The PDCCH carries dynamic allocatedresources, such as a physical resource block (PRB) and modulation andcoding scheme (MCS). A transmission time interval (TTI) which is a unittime for data transmission may be equal to a length of one subframe. Thelength of one subframe may be 1 ms.

The transport channel is classified into a common transport channel anda dedicated transport channel according to whether the channel is sharedor not. A DL transport channel for transmitting data from the network tothe UE includes a broadcast channel (BCH) for transmitting systeminformation, a paging channel (PCH) for transmitting a paging message, aDL-SCH for transmitting user traffic or control signals, etc. The DL-SCHsupports HARQ, dynamic link adaptation by varying the modulation, codingand transmit power, and both dynamic and semi-static resourceallocation. The DL-SCH also may enable broadcast in the entire cell andthe use of beamforming. The system information carries one or moresystem information blocks. All system information blocks may betransmitted with the same periodicity. Traffic or control signals of amultimedia broadcast/multicast service (MBMS) may be transmitted throughthe DL-SCH or a multicast channel (MCH).

A UL transport channel for transmitting data from the UE to the networkincludes a random access channel (RACH) for transmitting an initialcontrol message, a UL-SCH for transmitting user traffic or controlsignals, etc. The UL-SCH supports HARQ and dynamic link adaptation byvarying the transmit power and potentially modulation and coding. TheUL-SCH also may enable the use of beamforming. The RACH is normally usedfor initial access to a cell.

A MAC layer belongs to the L2. The MAC layer provides services to aradio link control (RLC) layer, which is a higher layer of the MAClayer, via a logical channel. The MAC layer provides a function ofmapping multiple logical channels to multiple transport channels. TheMAC layer also provides a function of logical channel multiplexing bymapping multiple logical channels to a single transport channel. A MACsublayer provides data transfer services on logical channels.

The logical channels are classified into control channels fortransferring control plane information and traffic channels fortransferring user plane information, according to a type of transmittedinformation. That is, a set of logical channel types is defined fordifferent data transfer services offered by the MAC layer. The logicalchannels are located above the transport channel, and are mapped to thetransport channels.

The control channels are used for transfer of control plane informationonly. The control channels provided by the MAC layer include a broadcastcontrol channel (BCCH), a paging control channel (PCCH), a commoncontrol channel (CCCH), a multicast control channel (MCCH) and adedicated control channel (DCCH). The BCCH is a downlink channel forbroadcasting system control information. The PCCH is a downlink channelthat transfers paging information and is used when the network does notknow the location cell of a UE. The CCCH is used by UEs having no RRCconnection with the network. The MCCH is a point-to-multipoint downlinkchannel used for transmitting MBMS control information from the networkto a UE. The DCCH is a point-to-point bi-directional channel used by UEshaving an RRC connection that transmits dedicated control informationbetween a UE and the network.

Traffic channels are used for the transfer of user plane informationonly. The traffic channels provided by the MAC layer include a dedicatedtraffic channel (DTCH) and a multicast traffic channel (MTCH). The DTCHis a point-to-point channel, dedicated to one UE for the transfer ofuser information and can exist in both uplink and downlink. The MTCH isa point-to-multipoint downlink channel for transmitting traffic datafrom the network to the UE.

Uplink connections between logical channels and transport channelsinclude the DCCH that can be mapped to the UL-SCH, the DTCH that can bemapped to the UL-SCH and the CCCH that can be mapped to the UL-SCH.Downlink connections between logical channels and transport channelsinclude the BCCH that can be mapped to the BCH or DL-SCH, the PCCH thatcan be mapped to the PCH, the DCCH that can be mapped to the DL-SCH, andthe DTCH that can be mapped to the DL-SCH, the MCCH that can be mappedto the MCH, and the MTCH that can be mapped to the MCH.

An RLC layer belongs to the L2. The RLC layer provides a function ofadjusting a size of data, so as to be suitable for a lower layer totransmit the data, by concatenating and segmenting the data receivedfrom a higher layer in a radio section. In addition, to ensure a varietyof quality of service (QoS) required by a radio bearer (RB), the RLClayer provides three operation modes, i.e., a transparent mode (TM), anunacknowledged mode (UM), and an acknowledged mode (AM). The AM RLCprovides a retransmission function through an automatic repeat request(ARQ) for reliable data transmission. Meanwhile, a function of the RLClayer may be implemented with a functional block inside the MAC layer.In this case, the RLC layer may not exist.

A packet data convergence protocol (PDCP) layer belongs to the L2. ThePDCP layer provides a function of header compression function thatreduces unnecessary control information such that data being transmittedby employing IP packets, such as IPv4 or Ipv6, can be efficientlytransmitted over a radio interface that has a relatively smallbandwidth. The header compression increases transmission efficiency inthe radio section by transmitting only necessary information in a headerof the data. In addition, the PDCP layer provides a function ofsecurity. The function of security includes ciphering which preventsinspection of third parties, and integrity protection which preventsdata manipulation of third parties.

A radio resource control (RRC) layer belongs to the L3. The RLC layer islocated at the lowest portion of the L3, and is only defined in thecontrol plane. The RRC layer takes a role of controlling a radioresource between the UE and the network. For this, the UE and thenetwork exchange an RRC message through the RRC layer. The RRC layercontrols logical channels, transport channels, and physical channels inrelation to the configuration, reconfiguration, and release of RBs. AnRB is a logical path provided by the L1 and L2 for data delivery betweenthe UE and the network. That is, the RB signifies a service provided theL2 for data transmission between the UE and E-UTRAN. The configurationof the RB implies a process for specifying a radio protocol layer andchannel properties to provide a particular service and for determiningrespective detailed parameters and operations. The RB is classified intotwo types, i.e., a signaling RB (SRB) and a data RB (DRB). The SRB isused as a path for transmitting an RRC message in the control plane. TheDRB is used as a path for transmitting user data in the user plane.

Referring to FIG. 2, the RLC and MAC layers (terminated in the eNB onthe network side) may perform functions such as scheduling, automaticrepeat request (ARQ), and hybrid automatic repeat request (HARQ). TheRRC layer (terminated in the eNB on the network side) may performfunctions such as broadcasting, paging, RRC connection management, RBcontrol, mobility functions, and UE measurement reporting andcontrolling. The NAS control protocol (terminated in the MME of gatewayon the network side) may perform functions such as a SAE bearermanagement, authentication, LTE_IDLE mobility handling, pagingorigination in LTE_IDLE, and security control for the signaling betweenthe gateway and UE.

Referring to FIG. 3, the RLC and MAC layers (terminated in the eNB onthe network side) may perform the same functions for the control plane.The PDCP layer (terminated in the eNB on the network side) may performthe user plane functions such as header compression, integrityprotection, and ciphering.

An RRC state indicates whether an RRC layer of the UE is logicallyconnected to an RRC layer of the E-UTRAN. The RRC state may be dividedinto two different states such as an RRC connected state (RRC_CONNECTED)and an RRC idle state (RRC_IDLE). When an RRC connection is establishedbetween the RRC layer of the UE and the RRC layer of the E-UTRAN, the UEis in RRC_CONNECTED, and otherwise the UE is in RRC_IDLE. Since the UEin RRC_CONNECTED has the RRC connection established with the E-UTRAN,the E-UTRAN may recognize the existence of the UE in RRC_CONNECTED andmay effectively control the UE. Meanwhile, the UE in RRC_IDLE may not berecognized by the E-UTRAN, and a CN manages the UE in unit of a TA whichis a larger area than a cell. That is, only the existence of the UE inRRC_IDLE is recognized in unit of a large area, and the UE musttransition to RRC_CONNECTED to receive a typical mobile communicationservice such as voice or data communication.

In RRC_IDLE state, the UE may receive broadcasts of system informationand paging information while the UE specifies a discontinuous reception(DRX) configured by NAS, and the UE has been allocated an identification(ID) which uniquely identifies the UE in a tracking area and may performpublic land mobile network (PLMN) selection and cell re-selection. Also,in RRC_IDLE state, no RRC context is stored in the eNB.

In RRC_CONNECTED state, the UE has an E-UTRAN RRC connection and acontext in the E-UTRAN, such that transmitting and/or receiving datato/from the eNB becomes possible. Also, the UE can report channelquality information and feedback information to the eNB. InRRC_CONNECTED state, the E-UTRAN knows the cell to which the UE belongs.Therefore, the network can transmit and/or receive data to/from UE, thenetwork can control mobility (handover and inter-radio accesstechnologies (RAT) cell change order to GSM EDGE radio access network(GERAN) with network assisted cell change (NACC)) of the UE, and thenetwork can perform cell measurements for a neighboring cell.

In RRC_IDLE state, the UE specifies the paging DRX cycle. Specifically,the UE monitors a paging signal at a specific paging occasion of everyUE specific paging DRX cycle. The paging occasion is a time intervalduring which a paging signal is transmitted. The UE has its own pagingoccasion.

A paging message is transmitted over all cells belonging to the sametracking area. If the UE moves from one TA to another TA, the UE willsend a tracking area update (TAU) message to the network to update itslocation.

When the user initially powers on the UE, the UE first searches for aproper cell and then remains in RRC_IDLE in the cell. When there is aneed to establish an RRC connection, the UE which remains in RRC_IDLEestablishes the RRC connection with the RRC of the E-UTRAN through anRRC connection procedure and then may transition to RRC_CONNECTED. TheUE which remains in RRC_IDLE may need to establish the RRC connectionwith the E-UTRAN when uplink data transmission is necessary due to auser's call attempt or the like or when there is a need to transmit aresponse message upon receiving a paging message from the E-UTRAN.

The UE which remains in RRC_IDLE persistently performs cell reselectionto find a better cell. In this case, the UE performs measurement andcell reselection by using frequency priority information. That is, theUE may determine which frequency will be preferentially considered whenperforming frequency measurement and cell reselection on the basis ofthe frequency priority information. The UE may receive the frequencypriority information by using system information or an RRC connectionrelease message. Or, the UE may receive the frequency priorityinformation from another RAT in inter-RAT cell reselection.

A non-access stratum (NAS) layer belongs to a higher layer of the RRClayer and serves to perform session management, mobility management,etc.

To manage mobility of the UE in the NAS layer, two states are defined,i.e., an EPS mobility management registered state (EMM-REGISTERED) andan EMM deregistered state (EMM-DEREGISTERED). These two states apply tothe UE and the MME. Initially, the UE is in the EMM-DEREGISTERED. Toaccess a network, the UE performs a procedure of registering to thenetwork through an initial attach procedure. If the attach procedure issuccessfully completed, the UE and the MME enter the EMM-REGISTERED.

To manage a signaling connection between the UE and the EPC, two statesare defined, i.e., an EPS connection management (ECM) idle state(ECM-IDLE) and an ECM connected state (ECM-CONNECTED). These two statesapply to the UE and the MME. When a UE in the ECM-IDLE establishes anRRC connection with the E-UTRAN, the UE enters the ECM-CONNECTED. Whenan MME in the ECM-IDLE establishes an S1 connection with the E-UTRAN,the MME enters the ECM-CONNECTED. When the UE is in the ECM-IDLE, theE-UTRAN does not have context information of the UE. Therefore, the UEin the ECM-IDLE performs a UE-based mobility related procedure such ascell selection or reselection without having to receive a command of thenetwork. On the other hand, when the UE is in the ECM-CONNECTED,mobility of the UE is managed by the command of the network. If alocation of the UE in the ECM-IDLE becomes different from a locationknown to the network, the UE reports the location of the UE to thenetwork through a tracking area update procedure.

It is known that different cause values may be mapped to the signaturesequence used to transmit messages between a UE and eNB and that eitherchannel quality indicator (CQI) or path loss and cause or message sizeare candidates for inclusion in the initial preamble.

When a UE wishes to access the network and determines a message to betransmitted, the message may be linked to a purpose and a cause valuemay be determined. The size of the ideal message may be also bedetermined by identifying all optional information and differentalternative sizes, such as by removing optional information, or analternative scheduling request message may be used.

The UE acquires necessary information for the transmission of thepreamble, UL interference, pilot transmit power and requiredsignal-to-noise ratio (SNR) for the preamble detection at the receiveror combinations thereof. This information must allow the calculation ofthe initial transmit power of the preamble. It is beneficial to transmitthe UL message in the vicinity of the preamble from a frequency point ofview in order to ensure that the same channel is used for thetransmission of the message.

The UE should take into account the UL interference and the UL path lossin order to ensure that the network receives the preamble with a minimumSNR. The UL interference can be determined only in the eNB, andtherefore, must be broadcast by the eNB and received by the UE prior tothe transmission of the preamble. The UL path loss can be considered tobe similar to the DL path loss and can be estimated by the UE from thereceived RX signal strength when the transmit power of some pilotsequence of the cell is known to the UE.

The required UL SNR for the detection of the preamble would typicallydepend on the eNB configuration, such as a number of Rx antennas andreceiver performance. There may be advantages to transmit the ratherstatic transmit power of the pilot and the necessary UL SNR separatelyfrom the varying UL interference and possibly the power offset requiredbetween the preamble and the message.

The initial transmission power of the preamble can be roughly calculatedaccording to the following formula:

Transmit power=TransmitPilot−RxPilot+ULInterference+Offset+SNRRequired

Therefore, any combination of SNRRequired, ULInterference, TransmitPilotand Offset can be broadcast. In principle, only one value must bebroadcast. This is essentially in current UMTS systems, although the ULinterference in 3GPP LTE will mainly be neighboring cell interferencethat is probably more constant than in UMTS system.

The UE determines the initial UL transit power for the transmission ofthe preamble as explained above. The receiver in the eNB is able toestimate the absolute received power as well as the relative receivedpower compared to the interference in the cell. The eNB will consider apreamble detected if the received signal power compared to theinterference is above an eNB known threshold.

The UE performs power ramping in order to ensure that a UE can bedetected even if the initially estimated transmission power of thepreamble is not adequate. Another preamble will most likely betransmitted if no ACK or NACK is received by the UE before the nextrandom access attempt. The transmit power of the preamble can beincreased, and/or the preamble can be transmitted on a different ULfrequency in order to increase the probability of detection. Therefore,the actual transmit power of the preamble that will be detected does notnecessarily correspond to the initial transmit power of the preamble asinitially calculated by the UE.

The UE must determine the possible UL transport format. The transportformat, which may include MCS and a number of resource blocks thatshould be used by the UE, depends mainly on two parameters, specificallythe SNR at the eNB and the required size of the message to betransmitted.

In practice, a maximum UE message size, or payload, and a requiredminimum SNR correspond to each transport format. In UMTS, the UEdetermines before the transmission of the preamble whether a transportformat can be chosen for the transmission according to the estimatedinitial preamble transmit power, the required offset between preambleand the transport block, the maximum allowed or available UE transmitpower, a fixed offset and additional margin. The preamble in UMTS neednot contain any information regarding the transport format selected bythe EU since the network does not need to reserve time and frequencyresources and, therefore, the transport format is indicated togetherwith the transmitted message.

The eNB must be aware of the size of the message that the UE intends totransmit and the SNR achievable by the UE in order to select the correcttransport format upon reception of the preamble and then reserve thenecessary time and frequency resources. Therefore, the eNB cannotestimate the SNR achievable by the EU according to the received preamblebecause the UE transmit power compared to the maximum allowed orpossible UE transmit power is not known to the eNB, given that the UEwill most likely consider the measured path loss in the DL or someequivalent measure for the determination of the initial preambletransmission power.

The eNB could calculate a difference between the path loss estimated inthe DL compared and the path loss of the UL. However, this calculationis not possible if power ramping is used and the UE transmit power forthe preamble does not correspond to the initially calculated UE transmitpower. Furthermore, the precision of the actual UE transmit power andthe transmit power at which the UE is intended to transmit is very low.Therefore, it has been proposed to code the path loss or CQI estimationof the downlink and the message size or the cause value In the UL in thesignature.

System information is described. It may be referred to Section 5.2.2 of3GPP TS 36.331 V8.7.0 (2009-09).

The system information includes essential information that needs to beknown to a UE to access a BS. Thus, the UE has to receive all systeminformation before accessing the BS. Further, the UE always has to havethe latest system information. Since the system information isinformation that must be known to all UEs in one cell, the BSperiodically transmits the system information.

The system information is classified into a master information block(MIB), a scheduled block (SB), and a system information block (SIB). TheMIB allows the UE to know a physical configuration (e.g., bandwidth) ofa specific cell. The SB reports transmission information (e.g., atransmission period or the like) of SIBs. The SIB is a group of aplurality of pieces of system information related to each other. Forexample, an SIB includes only information of a neighboring cell, andanother SIB includes only information of an uplink radio channel used bythe UE.

In general, a service provided by the network to the UE can beclassified into three types to be described below. Further, according towhich service can be provided, the UE recognizes a cell typedifferently. A service type is as follows.

-   1) Limited service: This service provides an emergency call and an    earthquake and tsunami warning system (ETWS), and can be provided in    an acceptable cell.-   2) Normal service: This service denotes a public use service for    general use, and can be provided in a suitable or normal cell.-   3) Operator service: This service denotes a service for a network    service provider, and a cell can be used only by the network service    provider and cannot be used by a normal user.

A cell type is as follows.

-   1) Acceptable cell: A UE can receive a limited service in this cell.    This cell is not barred from the perspective of the UE, and    satisfies a cell selection criterion of the UE.-   2) Suitable cell: The UE can receive a regular service in this cell.    This cell satisfies a condition of an acceptable cell, and also    satisfies additional conditions. Regarding the additional    conditions, this cell has to belong to a PLMN to which the UE can    access, and a tracking area update procedure of the UE must not be    barred in this cell. If a specific cell is a CSG cell, this cell    must be accessible by the UE as a CSG member.-   3) Barred cell: Information indicating that a cell is a barred cell    is broadcast in this cell by using system information.-   4) Reserved cell: Information indicating that a cell is a reserved    cell is broadcast in this cell by using system information.

While in RRC_IDLE, the UE selects a RAT for communicating with a publicland mobile network (PLMN) from which the UE intends to be served.Information about the PLMN and the RAT may be selected by a user of theUE. The user may use the information stored in a universal subscriberidentity module (USIM).

A UE selects a highest cell among a measured BS and cells having higherquality than a predetermined value. This procedure is referred as aninitial cell reselection, and performed by a UE turned on. The cellselection procedure will be described later. After the cell selection,the UE periodically receives system information from the BS. Thepredetermined value is a value defined in a communication system forensuring a physical signal quality in data transmission/reception.Therefore, the predetermined value may vary with a RAT to which the eachpredetermined value is applied.

The UE performs a network registration if needed. The UE registers selfinformation (i.e., International mobile Subscribe (MASI)) for beingserved by the network (i.e., paging). The UE does not register wheneverthe UE selects a cell. When the UE's own information about the networkis different from information about the network provided from the systeminformation, the UE performs the network registration procedure.

During RRC connection establishment procedure, a UE sends to a networkan RRC connection request message for requesting an RRC connection. Thenetwork sends an RRC connection setup message in response to the RRCconnection request. After receiving the RRC connection setup message,the UE enters an RRC connection mode. The UE sends to the network an RRCconnection setup complete message used to confirm successful completionof the RRC connection.

An RRC connection reconfiguration is used to modify an RRC connection.This is used to establish/modify/release an RB, to perform a handover,and to set up/modify/release a measurement.

A network sends to a UE an RRC connection reconfiguration message formodifying the RRC connection. In response to the RRC connectionreconfiguration, the UE sends to the network an RRC connectionreconfiguration complete message used to confirm successful completionof the RRC connection reconfiguration.

A procedure for selecting a cell by the UE is described. It may bereferred to Section 5.2 of 3GPP TS 36.304 V8.5.0 (2009-03).

If the UE is turned on or is camped on a cell, the UE may performprocedures for selecting/reselecting a cell having suitable quality inorder to receive a service. The UE in RRC_IDLE needs to be ready toreceive the service through the cell by selecting the cell havingsuitable quality all the time. For example, the UE that has been justturned on must select the cell having suitable quality so as to beregistered into a network. If the UE that has stayed in RRC_CONNECTEDenters into RRC_IDLE, the UE must select a cell on which the UE itselfis camped. As such, a process of selecting a cell satisfying a certaincondition by the UE in order to stay in a service waiting state such asRRC_IDLE is called a cell selection. The cell selection is performed ina state that the UE does not currently determine a cell on which the UEitself is camped in RRC_IDLE, and thus it is very important to selectthe cell as quickly as possible. Therefore, if a cell provides radiosignal quality greater than or equal to a predetermined level, the cellmay be selected in the cell selection process of the UE even though thecell is not a cell providing best radio signal quality.

If power is initially turned on, the UE searches for available PLMNs andselects a suitable PLMN to receive a service. Subsequently, the UEselects a cell having a signal quality and property capable of receivinga suitable service among the cells provided by the selected PLMN.

The cell selection process can be classified into two processes.

One process is an initial cell selection process, and in this process,the UE does not have previous information on radio channels. Therefore,the UE searches for all radio channels to find a suitable cell. In eachchannel, the UE searches for the strongest cell. Subsequently, if asuitable cell satisfying cell selection criteria is found, the UEselects the cell.

After the UE selects a certain cell through a cell selection process,the signal strength and quality between the UE and the BS may be changeddue to the change of the UE mobility and wireless environment.Therefore, if the quality of the selected cell deteriorates, the UE mayselect another cell providing better quality. If a cell is reselected inthis manner, a cell providing signal quality better than that of thecurrently selected cell is selected in general. This process is called acell reselection. A basic purpose of the cell reselection process isgenerally to select a cell providing best quality to the UE from theperspective of the radio signal quality.

In addition to the perspective of the radio signal quality, the networkmay notify the UE of a priority determined for each frequency. The UEthat has received the priority may consider this priority morepreferentially than the radio signal quality criteria during the cellreselection process.

As described above, there is a method of selecting or reselecting a cellbased on the signal property of the wireless environment. When a cell isselected for reselection in the cell reselection process, there may becell reselection methods as described below, based on the RAT andfrequency characteristics of the cell.

-   -   Intra-frequency cell reselection: A reselected cell is a cell        having the same center-frequency and the same RAT as those used        in a cell on which the UE is currently being camped.    -   Inter-frequency cell reselection: A reselected cell is a cell        having the same RAT and a different center-frequency with        respect to those used in the cell on which the UE is currently        being camped.    -   Inter-RAT cell reselection: A reselected cell is a cell using a        different RAT from a RAT used in the cell on which the UE is        currently being camped.

The principles of the cell reselection process are as follows.

First, the UE measures quality of a serving cell and a neighboring cellfor a cell reselection.

Second, the cell reselection is performed based on cell reselectioncriteria. The cell reselection criteria have following characteristicswith regard to the measurement of serving cells and neighboring cells.

The intra-frequency cell reselection is basically based on ranking. Theranking is an operation for defining a criterion value for evaluation ofthe cell reselection and for ordering cells according to a magnitude ofthe criterion value by using the criterion value. A cell having thehighest criterion is referred to as a best-ranked cell. The cellcriterion value is a value to which a frequency offset or a cell offsetis optionally applied on the basis of a value measured by the UE for acorresponding cell.

The inter-frequency cell reselection is based on a frequency priorityprovided by the network. The UE attempts to camp on at a frequencyhaving the highest priority. The network may provide the same frequencypriority to be commonly applied to UEs in a cell by using broadcastsignaling or may provide a frequency-specific priority to each UE byusing dedicated signaling for each UE.

For the inter-frequency cell reselection, the network may provideparameters (e.g., frequency-specific offsets) for use in cellreselection to the UE for each frequency.

For the intra-frequency cell reselection or the inter-frequency cellreselection, the network may provide a neighboring cell list (NCL) foruse in the cell reselection to the UE. The NCL includes cell-specificparameters (e.g., cell-specific offsets) used in the cell reselection.

For the intra-frequency or inter-frequency cell reselection, the networkmay provide the UE with a black list, i.e., a list of cells not to beselected in the cell reselection. The UE does not perform the cellreselection on cells included in the black list.

Measurement and measurement report is described.

It is necessary for a mobile communication system to support mobility ofa UE.

Therefore, the UE persistently measures quality of a serving cellproviding a current service and quality of a neighboring cell. The UEreports a measurement result to a network at a proper time. The networkprovides optimal mobility to the UE by using a handover or the like.

To provide information which can be helpful for a network operation of aservice provider in addition to the purpose of supporting the mobility,the UE may perform measurement with a specific purpose determined by thenetwork, and may report the measurement result to the network. Forexample, the UE receives broadcast information of a specific celldetermined by the network. The UE may report to a serving cell a cellidentify (also referred to as a global cell identity) of the specificcell, location identification information indicating a location of thespecific cell (e.g., a tracking area code), and/or other cellinformation (e.g., whether it is a member of a closed subscriber group(CSG) cell).

In a state of moving, if the UE determines that quality of a specificregion is significantly bad, the UE may report a measurement result andlocation information on cells with bad quality to the network. Thenetwork may attempt to optimize the network on the basis of themeasurement result reported from UEs which assist the network operation.

In a mobile communication system having a frequency reuse factor of 1,mobility is generally supported between different cells existing in thesame frequency band. Therefore, in order to properly guarantee the UEmobility, the UE has to properly measure cell information and quality ofneighboring cells having the same center frequency as a center frequencyof a serving cell. Measurement on a cell having the same centerfrequency as the center frequency of the serving cell is referred to asintra-frequency measurement. The UE performs the intra-frequencymeasurement and reports a measurement result to the network, so as toachieve the purpose of the measurement result.

A mobile communication service provider may perform a network operationby using a plurality of frequency bands. If a service of a communicationsystem is provided by using the plurality of frequency bands, optimalmobility can be guaranteed to the UE when the UE is able to properlymeasure cell information and quality of neighboring cells having adifferent center frequency from the center frequency of the servingcell. Measurement on a cell having the different center frequency fromthe center frequency of the serving cell is referred to asinter-frequency measurement. The UE has to be able to perform theinter-frequency measurement and report a measurement result to thenetwork.

When the UE supports measurement on a heterogeneous network, measurementon a cell of the heterogeneous network may be performed according to aconfiguration of a BS. Such a measurement on the heterogeneous networkis referred to as inter-RAT measurement. For example, RAT may include aGMS EDGE radio access network (GERAN) and a UMTS terrestrial radioaccess network (UTRAN) conforming to the 3GPP standard, and may alsoinclude a CDMA 2000 system conforming to the 3GPP2 standard.

For measurement report configuration, a UE receives measurementconfiguration information from a BS. A message including the measurementconfiguration information is referred to as a measurement configurationmessage. The UE performs measurement based on the measurementconfiguration information. If a measurement result satisfies a reportingcondition included in the measurement configuration information, the UEreports the measurement result to the BS. A message including themeasurement result is referred to as a measurement report message.

The measurement configuration information may include the followinginformation.

-   (1) Measurement object: The object is on which the UE performs the    measurements. The measurement object includes at least one of an    intra-frequency measurement object which is an object of    intra-frequency measurement, an inter-frequency measurement object    which is an object of inter-frequency measurement, and an inter-RAT    measurement object which is an object of inter-RAT measurement. For    example, the intra-frequency measurement object may indicate a    neighboring cell having the same frequency as a frequency of a    serving cell, the inter-frequency measurement object may indicate a    neighboring cell having a different frequency from a frequency of    the serving cell, and the inter-RAT measurement object may indicate    a neighboring cell of a different RAT from an RAT of the serving    cell.-   (2) Reporting configuration: This includes a reporting criterion and    a reporting format. The reporting criterion is used to trigger the    UE to send a measurement report and can either be periodical or a    single event description. The reporting format is a quantity that    the UE includes in the measurement report and associated information    (e.g., number of cells to report).-   (3) Measurement identify: Each measurement identity links one    measurement object with one reporting configuration. By configuring    multiple measurement identities, it is possible to link more than    one measurement object to the same reporting configuration, as well    as to link more than one reporting configuration to the same    measurement object. The measurement identity is used as a reference    number in the measurement report. The measurement identify may be    included in the measurement report to indicate a specific    measurement object for which the measurement result is obtained and    a specific reporting condition according to which the measurement    report is triggered.-   (4) Quantity configuration: One quantity configuration is configured    per RAT type. The quantity configuration defines the measurement    quantities and associated filtering used for all event evaluation    and related reporting of that measurement type. One filter can be    configured per measurement quantity.-   (5) Measurement gaps: Measurement gaps are periods that the UE may    use to perform measurements when downlink transmission and uplink    transmission are not scheduled.

To perform a measurement procedure, the UE has a measurement object, areporting configuration, and a measurement identity.

The BS can assign only one measurement object to the UE with respect toone frequency. Events for triggering measurement reporting are asfollows. It may be referred to Section 5.5.4 of 3GPP TS 36.331 V8.5.0(2009-03).

-   -   Event A1: Serving becomes better than threshold    -   Event A2: Serving becomes worse than threshold    -   Event A3: Neighbor becomes offset better than serving    -   Event A4: Neighbor becomes better than threshold    -   Event A5: Serving becomes worse than threshold1 and neighbor        becomes better than threshold2    -   Event B1: Inter RAT neighbor becomes better than threshold    -   Event B2: Serving becomes worse than threshold1 and inter RAT        neighbor becomes better than threshold2

If the measurement result of the UE satisfies the determined event, theUE transmits a measurement report message to the BS.

A PLMN is a network deployed and operated by mobile network operator(s).Each mobile network operator runs one or more PLMNs. Each PLMN can beidentified with the mobile country code (MCC) and the mobile networkcode (MNC). The PLMN information of a cell is broadcast in the systeminformation.

For PLMN selection, cell selection, and cell reselection, several typesof PLMNs are considered by UE.

-   -   Home PLMN (HPLMN): The PLMN whose MCC and the MNC matches the        MCC and the MNC of the UE's IMSI.    -   Equivalent HPLMN (EHPLMN): Any PLMN that is equivalent to HPLMN.    -   Registered PLMN (RPLMN): The PLMN for which location        registration is successful.    -   Equivalent PLMN (EPLMN): Any PLMN that is equivalent to RPLMN.

Each mobile service subscriber has a subscription with a HPLMN. When thenormal service is provided to UE by the HPLMN or the EHPLMN, the UE isnot in a roaming state. On the other hand, when the service is providedto UE by the PLMN other than HPLMN/EPHPLN, the UE is in a roaming state,and the PLMN is called visited PLMN (VPLMN).

When UE is powered on, PLMN selection is triggered. For the selectedPLMN, UE attempts to register the selected PLMN. If the registration issuccessful, the selected PLMN becomes RPLMN. Network can signal to theUE a list of PLMN for which the UE considers those PLMNs in the PLMNlist equivalent to its RPLMN. The PLMN equivalent to RPLMN is calledEPLMN. The UE that registered with network should be reachable by thenetwork at any time. If the UE is in ECM-CONNECTED (equivalently RRC_(—)CONNECTED), the network is aware of the cell the UE is being served.However, while the UE is in ECM-IDLE (equivalently RRC_IDLE), thecontext of the UE is not available at the eNB but stored in the MME. Inthis case, the location of the UE in ECM-IDLE is only known to the MMEat the granularity of a list of tracking Areas (TAs).

Wi-Fi protocols are described. Wi-Fi is a popular technology that allowsan electronic device to exchange data wirelessly (using radio waves)over a computer network, including high-speed Internet connections. TheWi-Fi Alliance defines Wi-Fi as any “wireless local area network (WLAN)products that are based on the IEEE 802.11 standards”. However, sincemost modern WLANs are based on these standards, the term “Wi-Fi” is usedin general English as a synonym for “WLAN”.

A device that can use Wi-Fi (such as a personal computer, video-gameconsole, smartphone, tablet, or digital audio player) can connect to anetwork resource such as the Internet via a wireless network accesspoint. Such an access point (or hotspot) has a range of about 20 meters(65 feet) indoors and a greater range outdoors. Hotspot coverage cancomprise an area as small as a single room with walls that block radiowaves or as large as many square miles—this is achieved by usingmultiple overlapping access points.

“Wi-Fi” is a trademark of the Wi-Fi Alliance and the brand name forproducts using the IEEE 802.11 family of standards. Only Wi-Fi productsthat complete Wi-Fi Alliance interoperability certification testingsuccessfully may use the “Wi-Fi CERTIFIED” designation and trademark.

Wi-Fi has had a checkered security history. Its earliest encryptionsystem, wired equivalent privacy (WEP), proved easy to break. Muchhigher quality protocols, Wi-Fi protected access (WPA) and WPA2, wereadded later. However, an optional feature added in 2007, called Wi-Fiprotected setup (WPS), has a flaw that allows a remote attacker torecover the router's WPA or WPA2 password in a few hours on mostimplementations. Some manufacturers have recommended turning off the WPSfeature. The Wi-Fi Alliance has since updated its test plan andcertification program to ensure all newly certified devices resistbrute-force AP PIN attacks.

The 802.11 family consist of a series of half-duplex over-the-airmodulation techniques that use the same basic protocol. The most popularare those defined by the 802.11b and 802.11g protocols, which areamendments to the original standard. 802.11-1997 was the first wirelessnetworking standard, but 802.11b was the first widely accepted one,followed by 802.11g and 802.11n. 802.11n is a new multi-streamingmodulation technique. Other standards in the family (c-f, h, j) areservice amendments and extensions or corrections to the previousspecifications.

802.11b and 802.11g use the 2.4 GHz ISM band, operating in the UnitedStates under Part 15 of the US Federal Communications Commission Rulesand Regulations. Because of this choice of frequency band, 802.11b and gequipment may occasionally suffer interference from microwave ovens,cordless telephones and Bluetooth devices. 802.11b and 802.11g controltheir interference and susceptibility to interference by usingdirect-sequence spread spectrum (DSSS) and OFDM signaling methods,respectively. 802.11a uses the 5 GHz U-NII band, which, for much of theworld, offers at least 23 non-overlapping channels rather than the 2.4GHz ISM frequency band, where adjacent channels overlap. Better or worseperformance with higher or lower frequencies (channels) may be realized,depending on the environment.

The segment of the radio frequency spectrum used by 802.11 variesbetween countries. In the US, 802.11a and 802.11g devices may beoperated without a license, as allowed in Part 15 of the FCC Rules andRegulations. Frequencies used by channels one through six of 802.11b and802.11g fall within the 2.4 GHz amateur radio band. Licensed amateurradio operators may operate 802.11b/g devices under Part 97 of the FCCRules and Regulations, allowing increased power output but notcommercial content or encryption.

FIG. 5 shows a graphical representation of Wi-Fi channels in 2.4 GHzband.

802.11 divides each of the above-described bands into channels,analogous to the way radio and TV broadcast bands are sub-divided. Forexample the 2.4000-2.4835 GHz band is divided into 13 channels spaced 5MHz apart, with channel 1 centered on 2.412 GHz and 13 on 2.472 GHz (towhich Japan added a 14^(th) channel 12 MHz above channel 13 which wasonly allowed for 802.11b). 802.11b was based on DSSS with a totalchannel width of 22 MHz and did not have steep skirts. Consequently onlythree channels do not overlap. Even now, many devices are shipped withchannels 1, 6 and 11 as preset options even though with the newer802.11g standard there are four non-overlapping channels—1, 5, 9 and 13.There are now four because the OFDM modulated 802.11g channels are 20MHz wide.

Availability of channels is regulated by country, constrained in part byhow each country allocates radio spectrum to various services. At oneextreme, Japan permits the use of all 14 channels for 802.11b, whileother countries such as Spain initially allowed only channels 10 and 11,and France only allowed 10, 11, 12 and 13. They now allow channels 1through 13. North America and some Central and South American countriesallow only 1 through 11.

In addition to specifying the channel centre frequency, 802.11 alsospecifies a spectral mask defining the permitted power distributionacross each channel. The mask requires the signal be attenuated aminimum of 20 dB from its peak amplitude at ±11 MHz from the centrefrequency, the point at which a channel is effectively 22 MHz wide. Oneconsequence is that stations can only use every fourth or fifth channelwithout overlap, typically 1, 6 and 11 in the Americas, and in theory,1, 5, 9 and 13 in Europe although 1, 6, and 11 is typical there too.Another is that channels 1-13 effectively require the band 2.401-2.483GHz, the actual allocations being, for example, 2.400-2.4835 GHz in theUK, 2.402-2.4735 GHz in the US, etc.

Most Wi-Fi devices default to regdomain 0, which means least commondenominator settings, i.e., the device will not transmit at a powerabove the allowable power in any nation, nor will it use frequenciesthat are not permitted in any nation.

The regdomain setting is often made difficult or impossible to change sothat the end users do not conflict with local regulatory agencies suchas the Federal Communications Commission.

Current 802.11 standards define “frame” types for use in transmission ofdata as well as management and control of wireless links.

Frames are divided into very specific and standardized sections. Eachframe consists of a MAC header, payload and frame check sequence (FCS).Some frames may not have the payload. The first two bytes of the MACheader form a frame control field specifying the form and function ofthe frame. The frame control field is further subdivided into thefollowing sub-fields:

-   -   Protocol Version: two bits representing the protocol version.        Currently used protocol version is zero. Other values are        reserved for future use.    -   Type: two bits identifying the type of WLAN frame. Control, data        and management are various frame types defined in IEEE 802.11.    -   Sub Type: Four bits providing addition discrimination between        frames. Type and Sub type together to identify the exact frame.    -   ToDS and FromDS: Each is one bit in size. They indicate whether        a data frame is headed for a distribution system. Control and        management frames set these values to zero. All the data frames        will have one of these bits set. However communication within an        independent basic service set (IBSS) network always set these        bits to zero.    -   More Fragments: The More Fragments bit is set when a packet is        divided into multiple frames for transmission. Every frame        except the last frame of a packet will have this bit set.    -   Retry: Sometimes frames require retransmission, and for this        there is a Retry bit which is set to one when a frame is resent.        This aids in the elimination of duplicate frames.    -   Power Management: This bit indicates the power management state        of the sender after the completion of a frame exchange. Access        points are required to manage the connection and will never set        the power saver bit.    -   More Data: The More Data bit is used to buffer frames received        in a distributed system. The access point uses this bit to        facilitate stations in power saver mode. It indicates that at        least one frame is available and addresses all stations        connected.    -   WEP: The WEP bit is modified after processing a frame. It is        toggled to one after a frame has been decrypted or if no        encryption is set it will have already been one.    -   Order: This bit is only set when the “strict ordering” delivery        method is employed. Frames and fragments are not always sent in        order as it causes a transmission performance penalty.

The next two bytes are reserved for the Duration ID field. This fieldcan take one of three forms: Duration, Contention-Free Period (CFP), andAssociation ID (AID).

An 802.11 frame can have up to four address fields. Each field can carrya MAC address. Address 1 is the receiver, Address 2 is the transmitter,Address 3 is used for filtering purposes by the receiver.

-   -   The Sequence Control field is a two-byte section used for        identifying message order as well as eliminating duplicate        frames. The first 4 bits are used for the fragmentation number        and the last 12 bits are the sequence number.    -   An optional two-byte Quality of Service control field which was        added with 802.11e.    -   The Frame Body field is variable in size, from 0 to 2304 bytes        plus any overhead from security encapsulation and contains        information from higher layers.    -   The frame check sequence (FCS) is the last four bytes in the        standard 802.11 frame. Often referred to as the cyclic        redundancy check (CRC), it allows for integrity check of        retrieved frames. As frames are about to be sent the FCS is        calculated and appended. When a station receives a frame it can        calculate the FCS of the frame and compare it to the one        received. If they match, it is assumed that the frame was not        distorted during transmission.

Management frames allow for the maintenance of communication. Somecommon 802.11 subtypes include:

-   -   Authentication frame: 802.11 authentication begins with the        wireless network interface controller (WNIC) sending an        authentication frame to the access point containing its        identity. With an open system authentication the WNIC only sends        a single authentication frame and the access point responds with        an authentication frame of its own indicating acceptance or        rejection. With shared key authentication, after the WNIC sends        its initial authentication request it will receive an        authentication frame from the access point containing challenge        text. The WNIC sends an authentication frame containing the        encrypted version of the challenge text to the access point. The        access point ensures the text was encrypted with the correct key        by decrypting it with its own key. The result of this process        determines the WNIC's authentication status.    -   Association request frame: sent from a station it enables the        access point to allocate resources and synchronize. The frame        carries information about the WNIC including supported data        rates and the SSID of the network the station wishes to        associate with. If the request is accepted, the access point        reserves memory and establishes an association ID for the WNIC.    -   Association response frame: sent from an access point to a        station containing the acceptance or rejection to an association        request. If it is an acceptance, the frame will contain        information such an association ID and supported data rates.    -   Beacon frame: Sent periodically from an access point to announce        its presence and provide the SSID, and other parameters for        WNICs within range.    -   Deauthentication frame: sent from a station wishing to terminate        connection from another station.    -   Disassociation frame: sent from a station wishing to terminate        connection. It's an elegant way to allow the access point to        relinquish memory allocation and remove the WNIC from the        association table.    -   Probe request frame: sent from a station when it requires        information from another station.    -   Probe response frame: sent from an access point containing        capability information, supported data rates, etc., after        receiving a probe request frame.    -   Reassociation request frame: A WNIC sends a reassociation        request when it drops from range of the currently associated        access point and finds another access point with a stronger        signal. The new access point coordinates the forwarding of any        information that may still be contained in the buffer of the        previous access point.    -   Reassociation response frame: sent from an access point        containing the acceptance or rejection to a WNIC reassociation        request frame. The frame includes information required for        association such as the association ID and supported data rates.

Control frames facilitate in the exchange of data frames betweenstations. Some common 802.11 control frames include:

-   -   Acknowledgement (ACK) frame: After receiving a data frame, the        receiving station will send an ACK frame to the sending station        if no errors are found. If the sending station doesn't receive        an ACK frame within a predetermined period of time, the sending        station will resend the frame.    -   Request to send (RTS) frame: The RTS and CTS frames provide an        optional collision reduction scheme for access points with        hidden stations. A station sends a RTS frame to as the first        step in a two-way handshake required before sending data frames.    -   Clear to send (CTS) frame: A station responds to an RTS frame        with a CTS frame. It provides clearance for the requesting        station to send a data frame. The CTS provides collision control        management by including a time value for which all other        stations are to hold off transmission while the requesting        stations transmits.

Data frames carry packets from web pages, files, etc., within the body,using RFC 1042 encapsulation and EtherType numbers for protocolidentification.

The BSS is the basic building block of an 802.11 wireless LAN. Ininfrastructure mode, a single AP together with all associated stations(STAs) is called a BSS. This is not to be confused with the coverage ofan access point, which is called basic service area (BSA). The accesspoint acts as a master to control the stations within that BSS. Thesimplest BSS consists of one access point and one station. In ad hocmode, a set of synchronized stations (one of which acts as master) formsa BSS.

With 802.11, it is possible to create an ad-hoc network of clientdevices without a controlling access point; the result is called anIBSS.

Each BSS is uniquely identified by what's called a basic service setidentification (BSSID). For a BSS operating in infrastructure mode, theBSSID is the MAC address of the wireless access point (WAP). For anIBSS, the BSSID is a locally administered MAC address generated from a46-bit random number. The individual/group bit of the address is set to0 (individual). The universal/local bit of the address is set to 1(local).

A BSSID with a value of all is is used to indicate the broadcast BSSID,which may only be used during probe requests.

An extended service set (ESS) is a set of one or more interconnectedBSSs and integrated local area networks that appear as a single BSS tothe logical link control layer at any station associated with one ofthose BSSs. The BSSs may work on the same channel, or work on differentchannels to boost aggregate throughput.

Each ESS is identified by a service set identifier (SSID). For an IBSS,the SSID is chosen by the client device that starts the network, andbroadcasting of the SSID is performed in a pseudo-random order by alldevices that are members of the network. The maximum length of the SSIDis currently 32 bytes long.

The UE may receive the assistance information, such as thresholds, 3GPPaccess network cell identifiers, for interworking between the 3GPPaccess network and the non-3GPP access network from the network througha dedicated signaling and/or broadcast signaling. The assistanceinformation received through the dedicated signaling (hereinafter,dedicated assistance information) may be used to steer traffic ofspecific UEs which generates high load in the 3GPP access network. A UEto which the radio access network (RAN) gave aggressive dedicatedthresholds (i.e., promoting steering from the 3GPP access network to thenon-3GPP access network) would steer the traffic to the non-3GPP accessnetwork and then may become inactive in the 3GPP access network. Due tothe inactivity in the 3GPP access network, the UE would enter RRC_IDLE.However, if the UE applies the assistance information received throughthe broadcast signaling (hereinafter, broadcast assistance information)right after entering RRC_IDLE, it would be possible that the traffic ofthe UE is steered back to the 3GPP access network again by theassistance information received through the broadcast signaling. Thatis, it may cause a ping-pong problem due to the dedicated assistanceinformation and the broadcast assistance information.

In order to avoid the ping-pong problem described above, a method forapplying assistance information for traffic steering between a 3GPPaccess network and a non-3GPP access network, received through adedicated signaling and a broadcast signaling, according to anembodiment of the present invention is described. According to theembodiment of the present invention, a UE may apply dedicated assistanceinformation for a specific period of time even after the UE entersRRC_IDLE in order to avoid the ping-pong problem. By utilizing thededicated assistance information by the UE even after entering RRC_IDLEfor a specific period of time, the operator can effectively steer thetraffic of UEs in RRC_IDLE as well as UEs in RRC_CONNECTED between the3GPP access network and the non-3GPP access network.

While the UE is staying in RRC_CONNECTED, the UE may be given theassistance information for traffic steering between the 3GPP accessnetwork and non-3GPP access network through the dedicated signaling atany point of time. The dedicated assistance information may includevalidity information. The validity information will be described later.The dedicated assistance information is considered as valid when avalidity condition by the validity information is met. If the dedicatedassistance information is considered as valid, the UE applies thededicated assistance information. Otherwise, the UE applies theassistance information received through the broadcast signaling.

The UE may be given the assistance information through any downlinkdedicated signaling, such as an RRC connection release message or an RRCconnection reconfiguration message, etc. If the UE in RRC_IDLE has validdedicated assistance information, the UE may stop reading systeminformation regarding traffic steering between the 3GPP access networkand the non-3GPP access network even if the network broadcasts theassistance information for traffic steering through the broadcastsignaling. If the validity condition by the validity information is notmet any more (e.g., a validity timer expires) during RRC_IDLE, the UE inRRC_IDLE may read the system information regarding traffic steeringbetween the 3GPP access network and the non-3GPP access network.

The assistance information may include at least one of followings.

-   -   Thresholds regarding the 3GPP access network: For frequency        division duplex (FDD), the thresholds regarding the 3GPP access        network may include LTE reference signal received power (RSRP)        threshold and/or UMTS common pilot channel (CPICH) received        signal code power (RSCP) threshold. Alternatively, for FDD, the        thresholds regarding the 3GPP access network may include LTE        reference signal received quality (RSRQ) threshold and/or UMTS        CPICH Ec. For time division duplex (TDD), the thresholds        regarding the 3GPP access network may include UMTS primary        common control physical channel (PCCPCH) RSCP threshold. The UE        may perform traffic steering between the 3GPP access network and        the non-3GPP access network after comparing the threshold and        measured signal level.    -   Thresholds regarding the non-3GPP access network: The thresholds        regarding the non-3GPP access network may include at least one        of WLAN channel utilization in the BSS load, available WLAN DL        and UL backhaul data rate or WLAN signal power/quality (e.g.,        received channel power indicator (RCPI), received signal to        noise indicator (RSNI), received signal strength indicator        (RSSI)). The UE may perform traffic steering between the 3GPP        access network and the non-3GPP access network after comparing        the threshold and the acquired load information.    -   Identifiers of the non-3GPP access network    -   Traffic routing information: The traffic routing information may        include at least one of offloadable bearer        information/Non-offloadable bearer information, offloadable        access point name (APN) information/Non-offloadable APN        information, or offloadable IP flow information/Non-offloadable        IP flow information.    -   Validity condition information: The validity condition        information may include at least one of time value during which        the assistance information is considered as valid, or area        information in which the assistance information is considered as        valid.

The validity information is described in detail. As described above, thevalidity information may include timer based validity information and/orarea based validity information.

At first, timer based validity information is described. The dedicatedassistance information may be considered as valid for a validity timeindicated by the validity information (e.g., x seconds/minutes) sincethe dedicated assistance information is received. That is, the timer maystart with the configured/fixed value when the UE receives the dedicatedassistance information. Even if the UE enter RRC_IDLE, the UE mayconsider the dedicated assistance information as valid if the timer isstill running Even if a serving cell is changed due to e.g., handover ora cell (re)selection, the dedicated assistance information may be stillconsidered as valid until the timer expires.

Alternatively, the dedicated assistance information is considered asvalid during RRC_CONNECTED unless the dedicated assistance informationis newly provided. Upon entering RRC_IDLE, the dedicated assistanceinformation is considered as valid according to the validityinformation. That is, the timer may start with the configured/fixedvalue upon entering RRC_IDLE before successfully establishing RRCconnection. The UE may apply the dedicated assistance information uponentering RRC_IDLE, until timer with the configured/fixed expires sincethe UE enters RRC_IDLE. Even if a serving cell is changed, the dedicatedassistance information may be still considered as valid until the timerexpires.

Alternatively, the dedicated assistance information may be considered asvalid during this RRC connection. Alternatively, the dedicatedassistance information may be considered as valid during RRC_IDLEafterwards. The network may indicate via the dedicated signaling whetherthe dedicated assistance information is valid or not during RRC_IDLE.

At second, area based validity information is described. The dedicatedassistance information may be considered as valid only within in acurrent cell. If a serving cell is changed due to e.g., handover or cell(re)selection, the dedicated assistance information may be considered asinvalid. Alternatively, the dedicated assistance information may beconsidered as valid within a list of cells that are also informed toUEs. Alternatively, the dedicated assistance information may beconsidered as valid within a list of tracking area codes that are alsoinformed to UEs. The list of tracking area codes may be different fromthe normal list of tracking area codes, which is used to prevent toofrequent UE location updates.

The timer based validity information may be confined within the areabased validity information. If the UE moves out of the validity areaindicated by the area based validity information, the timer mayautomatically expire. Or, it is possible that the network configures theUE about which alternative above should be applied.

If the UE determines that the dedicated assistance information is notvalid, the UE may release the dedicated assistance information and clearthe timer.

When the dedicated assistance information is not considered as valid anymore, the UE may notify the network of the stored dedicated assistanceinformation and expiring of the dedicated assistance information. And,the UE may remove the stored dedicated assistance information. If the UEis in RRC_IDLE when the dedicated assistance information is notconsidered as valid any more, the UE may establish the RRC connection.The above information may be transmitted to the network using any ULmessage including an RRC connection establishment message.Alternatively, if the UE establishes the RRC connection before theexpiry of validity condition of the dedicated assistance information,the UE may notify the network of the dedicated assistance informationand the validity information included in the dedicated assistanceinformation. Upon receiving the dedicated assistance information and thevalidity information, the network may indicate whether to remove/applythe stored dedicated assistance information. Alternatively, afterreporting, the UE may autonomously remove the stored dedicatedassistance information.

Meanwhile, when the UE performs inter-cell/eNB handover, the source(e)NB may forward the dedicated assistance information for the UE to thetarget cell/(e)NB. If the UE performs the (re)selection while thededicated assistance information is considered as valid, the UE mayestablish RRC connection upon cell (re)selection and inform the networkof the valid dedicated assistance information.

FIG. 6 shows an example of a method for applying assistance informationfor traffic steering according to an embodiment of the presentinvention.

In step S100, the UE receives first assistance information for trafficsteering between through a dedicated signaling. In step S110, the UEreceives second assistance information for traffic steering through abroadcast signaling. In step S120, the UE starts a timer upon enteringan idle mode. In step S130, the UE applies the first assistanceinformation received through the dedicated signaling until the timerexpires. When the timer expires, the UE releases the first assistanceinformation received through the dedicate signaling. In step S140, theUE applies the second assistance information received through thebroadcast signaling after the timer expires.

FIG. 7 shows an example of a method for applying assistance informationfor traffic steering according to another embodiment of the presentinvention.

In step S200, the eNB may transmit the broadcast assistance informationfor traffic steering between the 3GPP access network and the non-3GPPaccess network. Upon receiving the broadcast assistance information, theUE may apply the broadcast assistance information.

In step S210, while the UE is in RRC_CONNECTED, the UE is given thededicated assistance information for traffic steering between the 3GPPaccess network and the non-3GPP access network, with the validity timervalue.

In step S220, during RRC_CONNECTED, the UE performs traffic steeringbased on the dedicated assistance information.

Due to traffic steering from the 3GPP access network to the non-3GPPaccess network, there is no active traffic in the 3GPP access network sothat the UE transits to RRC_IDLE. In step S230, upon transiting toRRC_IDLE, the UE sets the timer with the received validity timer valueand initiates the timer.

In step S240, during RRC_IDLE, the UE determines whether the dedicatedassistance information is still valid. That is, if the timer is stillrunning, the UE determines that the dedicated assistance information isvalid. In step S250, if there is valid dedicated assistance information,the UE performs traffic steering based on the dedicated assistanceinformation.

In step S260, if the dedicated assistance information is not valid anymore, the UE in RRC_IDLE establishes the RRC connection. That is, if thetimer expires, the UE in RRC_IDLE establishes the RRC connection. And instep S270, the UE notifies the eNB of the dedicated assistanceinformation and expiring of the dedicated assistance information. And,the UE may remove the dedicated assistance information.

In step S280, the eNB may provide new dedicated assistance informationto the UE. Then, the UE may receive and apply the new dedicatedassistance information.

FIG. 8 shows an example of a method for applying assistance informationfor traffic steering according to another embodiment of the presentinvention.

In step S300, while the UE is in RRC_CONNECTED, the UE is given theassistance/policy information for traffic steering between the 3GPPaccess network and non-3GPP access network through dedicated signalingat any point of time. The dedicated assistance information may be validwithin validity scope. If the assistance information is also providedwith broadcast signaling (e.g., through system information), the UE mayread the broadcast assistance information. However, the UE may overridebroadcasted assistance information with the dedicated assistanceinformation. Otherwise, the UE may apply the broadcast assistanceinformation.

The UE may be given the dedicated assistance information when the UEtransits from RRC_CONNECTED to RRC_IDLE. The dedicated assistanceinformation may be included in an RRC connection release message or anRRC connection reconfiguration message. Further, the validity scope maybe applied regardless of change of RRC state. In other words, even ifthe UE transits from RRC_IDLE to RRC_CONNECTED or vice versa, the UE maykeep the dedicated assistance information. When the eNB provides thededicated assistance information, the eNB may provide the indicationindicating that the dedicated assistance information is applicable tonext RRC_IDLE. In this case, the UE may perform traffic steering basedon the dedicated assistance information when the UE transits to nextRRC_IDLE as well as when the UE stays in RRC_CONNECTED. Otherwise, theUE performs traffic steering based on the dedicated assistanceinformation only when the UE stays in RRC_CONNECTED. Further, thebroadcast assistance information may be only applied to the UE when theUE stays in RRC_IDLE.

In step S310, after receiving the dedicated assistance information, theUE performs the traffic steering according to the dedicated assistanceinformation.

In step S320, the UE transits to RRC_IDLE.

In step S330, during staying in RRC_IDLE and RRC_CONNECTED, the UEdetermines whether the dedicated assistance information is still valid.

In step S340, if the validity of the dedicated assistance informationexpires during RRC_IDLE, the UE establishes the RRC connection. And, instep S350, the UE notifies the network of the dedicated assistanceinformation and expiring of the dedicated assistance information. Theabove information may be transmitted to the network during RRCconnection establishment procedure. And the UE may remove the storeddedicated assistance information.

If the UE establishes the RRC connection before the validity of thededicated assistance information, the UE may notify the network of thevalidity information of the dedicated assistance information. If thevalidity of the dedicated assistance information expires duringRRC_CONNECTED, the UE may notify the network of the dedicated assistanceinformation and expiring of the dedicated assistance information. If theUE establishes the RRC connection before the expiry of the dedicatedassistance information, the UE may remove the stored dedicatedassistance information even though the UE considers the dedicatedinformation as still valid. In this case, the UE in RRC_CONNECTED maynot perform traffic steering until the network newly provides thededicated assistance information if the broadcasted assistanceinformation is only applied to the UE in RRC_IDLE.

In step S360, the network may provide updated dedicated assistanceinformation to the UE. Then, the UE may receive and apply the updateddedicated assistance information.

When the UE performs inter-eNB handover, the source (e)NB may forwardthe dedicated assistance information to the target (e)NB. The validityis kept on regardless of RRC state of the UE. If the UE performs the(re)selection while the dedicated assistance information is valid, theUE may establish RRC connection and inform the network of the validdedicated assistance information. If the UE performs the (re)selectionwhile the dedicated assistance information is valid, the UE may clearthe valid dedicated assistance information.

FIG. 9 shows a wireless communication system to implement an embodimentof the present invention.

An eNB 800 may include a processor 810, a memory 820 and a radiofrequency (RF) unit 830. The processor 810 may be configured toimplement proposed functions, procedures and/or methods described inthis description. Layers of the radio interface protocol may beimplemented in the processor 810. The memory 820 is operatively coupledwith the processor 810 and stores a variety of information to operatethe processor 810. The RF unit 830 is operatively coupled with theprocessor 810, and transmits and/or receives a radio signal.

A UE 900 may include a processor 910, a memory 920 and a RF unit 930.The processor 910 may be configured to implement proposed functions,procedures and/or methods described in this description. Layers of theradio interface protocol may be implemented in the processor 910. Thememory 920 is operatively coupled with the processor 910 and stores avariety of information to operate the processor 910. The RF unit 930 isoperatively coupled with the processor 910, and transmits and/orreceives a radio signal.

The processors 810, 910 may include application-specific integratedcircuit (ASIC), other chipset, logic circuit and/or data processingdevice. The memories 820, 920 may include read-only memory (ROM), randomaccess memory (RAM), flash memory, memory card, storage medium and/orother storage device. The RF units 830, 930 may include basebandcircuitry to process radio frequency signals. When the embodiments areimplemented in software, the techniques described herein can beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The modules can be stored inmemories 820, 920 and executed by processors 810, 910. The memories 820,920 can be implemented within the processors 810, 910 or external to theprocessors 810, 910 in which case those can be communicatively coupledto the processors 810, 910 via various means as is known in the art.

In view of the exemplary systems described herein, methodologies thatmay be implemented in accordance with the disclosed subject matter havebeen described with reference to several flow diagrams. While forpurposed of simplicity, the methodologies are shown and described as aseries of steps or blocks, it is to be understood and appreciated thatthe claimed subject matter is not limited by the order of the steps orblocks, as some steps may occur in different orders or concurrently withother steps from what is depicted and described herein. Moreover, oneskilled in the art would understand that the steps illustrated in theflow diagram are not exclusive and other steps may be included or one ormore of the steps in the example flow diagram may be deleted withoutaffecting the scope and spirit of the present disclosure.

What is claimed is:
 1. A method for applying, by a user equipment (UE),assistance information for traffic steering between a 3rd generationpartnership project (3GPP) access network and a non-3GPP access networkin a wireless communication system, the method comprising: receivingfirst assistance information for traffic steering through a dedicatedsignaling from an eNodeB (eNB); receiving second assistance informationfor traffic steering through a broadcast signaling from the eNB;starting a timer upon entering an idle mode; applying the firstassistance information received through the dedicated signaling untilthe timer expires; and applying the second assistance informationreceived through the broadcast signaling after the timer expires.
 2. Themethod of claim 1, wherein the first assistance information includes atime value for the timer which indicates a period of time during whichthe first assistance information is valid.
 3. The method of claim 1,wherein the first assistance information is valid in a cell from whichthe first assistance information is received.
 4. The method of claim 1,further comprising: releasing the first assistance information upondetermining that the first assistance information is invalid.
 5. Themethod of claim 4, wherein it is determined that first assistanceinformation is invalid when a serving cell is changed.
 6. The method ofclaim 5, wherein the serving cell is changed when handover, cellselection or cell reselection is performed.
 7. The method of claim 1,wherein the first assistance information includes area informationindicating an area in which the first assistance information is valid.8. The method of claim 1, wherein the first assistance informationincludes at least one of thresholds regarding the 3GPP access network,thresholds regarding the non-3GPP access network, identifiers of thenon-3GPP access network, or traffic routing information.
 9. The methodof claim 1, wherein the second assistance information includes at leastone of thresholds regarding the 3GPP access network, thresholdsregarding the non-3GPP access network, identifiers of the non-3GPPaccess network, or traffic routing information.
 10. The method of claim1, wherein the first assistance information is received via a radioresource control (RRC) connection reconfiguration message.
 11. Themethod of claim 1, wherein the second assistance information is receivedvia system information.
 12. The method of claim 1, wherein the applyingthe first assistance information includes performing traffic steeringfrom the 3GPP access network to the non-3GPP access network or from thenon-3GPP access network to the 3GPP access network based on the firstassistance information.
 13. The method of claim 1, wherein the applyingthe second assistance information includes performing traffic steeringfrom the 3GPP access network to the non-3GPP access network or from thenon-3GPP access network to the 3GPP access network based on the secondassistance information.
 14. The method of claim 1, further comprising:establishing an RRC connection with the eNB after the timer expires; andtransmitting the first assistance information and the expiry of thefirst assistance information upon establishing the RRC connection withthe eNB.
 15. A user equipment (UE) in a wireless communication system,the UE comprising: a radio frequency (RF) unit for transmitting orreceiving a radio signal; and a processor coupled to the RF unit, andconfigured to: receive first assistance information for traffic steeringbetween a 3rd generation partnership project (3GPP) access network and anon-3GPP access network through a dedicated signaling from an eNodeB(eNB); receive second assistance information for traffic steeringthrough a broadcast signaling from the eNB; start a timer upon enteringan idle mode; apply the first assistance information received throughthe dedicated signaling until the timer expires; and apply the secondassistance information received through the broadcast signaling afterthe timer expires.